Question 1

Which of the following statements best explains why viruses are considered obligatory intracellular parasites?

Accepted Answer

They require living host cells to multiply because they lack ribosomes and an ATP-generating mechanism.

Question 2

A scientist is attempting to grow a newly discovered animal virus in the laboratory. Which of the following methods would be LEAST appropriate for this purpose?

Accepted Answer

Inoculating the virus into a bacterial culture.

Question 3

Which of the following best describes the function of viral spikes?

Accepted Answer

They facilitate attachment to specific host cell receptors.

Question 4

A patient is diagnosed with a persistent viral infection that gradually worsens over years and is ultimately fatal. Which virus is most likely responsible for this type of infection?

Accepted Answer

Measles virus causing subacute sclerosing panencephalitis

Question 5

Which of the following is a unique feature of the lysogenic cycle of bacteriophage lambda (λ) compared to the lytic cycle?

Accepted Answer

The phage DNA is incorporated into the host genome as a prophage.

Question 6

Which of the following viruses is correctly matched with its genome type and associated disease?

Accepted Answer

Herpesviridae: double-stranded DNA, causes chickenpox

Question 7

Which of the following best describes the process of specialized transduction?

Accepted Answer

Transfer of specific bacterial genes by a lysogenic phage during excision from the host genome.

Question 8

A virus with a single-stranded RNA genome that acts directly as mRNA for protein synthesis belongs to which group in the Baltimore classification?

Accepted Answer

Group IV: (+) ssRNA viruses

Question 9

Which of the following laboratory techniques is most useful for detecting and identifying a virus based on its interaction with specific antibodies?

Accepted Answer

ELISA (enzyme-linked immunosorbent assay)

Question 10

Which of the following statements about prions is correct?

Accepted Answer

Prions cause disease by inducing misfolding of normal host proteins.

Question 11

A patient develops cervical cancer years after a viral infection. Which virus is most likely responsible, and what is the mechanism?

Accepted Answer

Human papillomavirus (HPV); integration of viral DNA into host genome leading to oncogene activation

Question 12

Which of the following best explains why plant viruses often require wounds or insect vectors to infect plant cells?

Accepted Answer

Plant cell walls are generally impermeable to viruses.

Question 13

Which of the following is a correct sequence of events in the lytic cycle of a T-even bacteriophage?

Accepted Answer

Attachment → Penetration → Biosynthesis → Maturation → Release

Question 14

Which of the following best describes the role of reverse transcriptase in the replication of retroviruses?

Accepted Answer

It synthesizes DNA from an RNA template.

Question 15

A laboratory technician observes clear zones (plaques) on a bacterial lawn after infection with a bacteriophage. What does each plaque represent?

Accepted Answer

A single virus particle that initiated infection and subsequent lysis of bacteria

Question 16

Which of the following is a distinguishing feature of enveloped viruses compared to nonenveloped viruses?

Accepted Answer

They acquire a lipid membrane from the host cell during budding.

Question 17

Which of the following best describes the process of viral uncoating in animal viruses?

Accepted Answer

Separation of the viral nucleic acid from its capsid by viral or host enzymes

Question 18

Which of the following is a correct statement about viroids?

Accepted Answer

Viroids are short pieces of naked RNA that cause disease in plants.

Question 19

Which of the following is a potential outcome of lysogeny in bacteria infected with a temperate phage?

Accepted Answer

The host cell acquires new properties, such as toxin production, due to phage conversion.

Viruses, Viroids, and Prions: Structure, Classification, and Pathogenesis

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